Electric switch



Feb. 24,1942;

w. HARLOW ELECTRIC SWITCH ,Filed March 19, 1941 Fig.2

, currents in the blades.

under extremely high current conditions, such,

- Patented Feb. 24, 1942 UNITED STATES PATENT OFFICE ELECTRIC SWITCH Winton G. Harlow, Springfield, Pa., assignor to General Electric Company, a corporation of New York Application March 19, 1941, Serial No. 384,112

6 Claims.

My invention relates to improvements in electric switches and more particularly disconnectnecessary to use multiple blade disconnecting switches the several blades of which are spaced to insure better cooling conditions. Since the blades lie parallel to each other when in the current conducting position, large attractive forces are produced by the magnetic fields due to the These forces especially as occur during short-circuits, cause the blades to vibrate and may even permanently deform the blades. Such vibrations and deformation produce contact burning, and the switches may quickly be rendered useless. If suitable operating mechanisms are installed so that the blades can be moved simultaneously, then the blades can be cross braced one to the other to maintain their parallelism even under heavy. currents. This requires a variety of'bracing members dependent on the number of blades in the switch and the size of the blades. In consequence, more parts have to be made and carried in stock because different current carrying capacities require either different numbers of blades of the same size or difierent sizes of blades. Moreover, when contact adjustments have to be made, it is necessary to remove the cross bracing and adjust each blade separately. 'However, when the cross bracing is replaced, much care is necessary in order to avoid disturbing the alignment of the blades and thus upsetting the contact adjustments. 7

If the switches are hook operatedby hand as is more generally the case, then it is in many cases not desirable to operate more than one blade at a time because of the friction load involved in closing and opening including the release of the usual switch latch for preventing the opening of the switch by the magnetic loop expansion effect which is greatlyaccentuated with heavy currents. If the blades have to be operated independently, then any arrangement for bracing the blades against vibration and deformation by the attractive forces due to currents in the same direction in parallel conductors must not interfere with such individual blade movements. Also the bracing must be capable of adjustment so as successfully to resist blade vibration and deformation without interfering with the contact adjustment.

One object of my invention is to provide a simple and economical unitary bracing arrangement which is universally applicable to multiple blade switches of different sizes and capacities whether the blades are actuated simultaneously or are operated independently. Another object of my invention is to provide a unitary bracing arrangement which is not only effective to brace the separate blades but also to brace the parallel blade elements of each blade when the blade is composed of one or more such elements. A further object of my invention is to provide a bracing arrangement which does not interfere with the opening and closing of the blades whether they are actuated simultaneously or independently. A still further object of my invention is to provide a unitary bracing arrangement which can be readily adjusted for each blade without disturbing the contact adjustment of the blade itself or other blades and without disturbing the adjustment of the bracing arrangements of the other blades. These and other objects of my invention will appear in more detail hereinafter.

In accordance with my invention, I provide a unitary bracing arrangement comprising a bracing member which is adjustably positioned on the es having blades made up of a plurality of blade elements, further bracing means for each group of blade elements so as to prevent vibration and deformation of such elements by reason of their parallel position in space while conducting electric current in the same direction.

My invention will be better understood from the following description when considered in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the accompanying drawing Fig. 1 is a vertical side elevation of a disconnecting switch embodying my invention; Fig. 2 is a vertical front elevationof the switch shown in Fig. 1; and

, bers 5, arranged in one position to conduct current in parallel paths between terminals 6 and I and in another position to provide a gap between these terminals, which are suitably supported on insulators 8 mounted. on a base 9. As illustrated,

' .each of the conducting members 5 comprises a group of substantially parallel spaced blade elements which are pivoted for movement about a common axis in on one of the terminals 8 and engageable with "the other terminal I to conduct current from one terminal to the other. For this purpose the terminal 8 comprises a plurality of hinge posts H on each of which two blade elements are pivoted by suitable means such as a bolt l2 and resilient washers l3 ina manner well known to the art. The terminal I is provided with a plurality of contact tongues l4, one for each pair of blade elements. Suitable contact between each tongue l4 and its cooperating blade elements is eiiected by bolts I5 and resilient washers IS in a manner well known to the art. In the switch closed or conducting position of the blades 5 all of the blade elements are physically parallel in space.

In order to prevent each pair of blade elements 5 from flying open under the magnetic loop expansion effect due to heavy currents, a switch latch of the hook operated type may be provided such as disclosed for example in United States Letters Patent 1,755,083 issued April 15, 1930:-

As illustrated, this blade holding device comprises blade latches which are pivotally mounted on the terminal I and biased to hook over a blade extension member i8. Each latch is provided with a projection IS in the path of movement of a lug 20 on a pivoted switch operating eye 2| pivoted at 22 on the blade extension l8. Movement of the operating eye 2| clockwise, as viewed in Fig. 1, causes the lug 20 to engage the corresponding latch projection l9 and release the associated latch from the blade so that further pull on the eye 2i causes the opening of the blade.

In order to prevent vibration and deformation of the blades particularly when they are conjacent member when the members are in the current conducting position. Although the bracing elements 23 may be so set that they actually touch each other in the closed position of the switch, they can be substantially equally effective if there is a slight space between them since they will still limit the amount of deflection that the blade member may take under short-circuit conditions. In either case one bracing element practically abuts the adjacent bracing element.

The bracing elements 23 may be threaded as shown and secured in position on the conducting members by suitable means such as nuts 24 so that each bracing element 23 can be adjusted independently of the others. In orderto maintain the adjustment once it is made, each oi. the nuts 24 may be provided with suitable holding means such as set screw 25. The ends of the bracing elements may be rounded as shown in order to avoid any interference between abutting elements when the conducting members are independently movable. This allows a very close adjustment of the bracing elements 23 without danger of interference by reason of slight wear or play in the motion of the parts which might tend to produce at some point in the movement of the members a slight overlap in the bracing elements.

When the conducting members comprise a group of parallel blade elements, for example, two, as shown in the drawing, these are subject to vibration and deformation when conducting current and must be supported to prevent such vibration. Consequently, each group requires its own independent bracing. In accordance with my invention, I accomplish this by spacing means associated with the bracing element 23. As shown, this spacing means comprises a bushing 26 through which the bracing element extends, the length of the bushing being equal to the desired spacing of the blade elements. Preferably the bushing 26 slides freely on the bracing element 23 which also preferably is movable free- 1y through the blade elements except when the clamping nuts 24 are tightened. With this arrangement, it will be obvious that the adjustment of the bracing elements 23 relatively to each other can be accomplished without in any way interfering with adjustment of the blade elements themselves- Moreover, the adjustment of each bracing element 23 can be effected without in any way interfering with the contact or hinge adjustments.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangements shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising two terminals, a plurality of movable spaced elongated conducting members for conducting electric current between said terminals, said members being physically parallel while in the current conducting position, and means for preventing deformation of said members while they are conducting current comprising a bracing element carried by each of said members at a point intermediate their points of engagement with said terminals, each of said elements being so proportioned and positioned that the elements of adjacent members practically abut each other when the members are in the current conducting position.

2. An electric switch comprising two terminals, a plurality of independently movable spaced elongated conducting members pivoted for movement about a common axis on one of said termi nals and engageable with the other of said terminals for conducting electric current in parallel paths between the terminals, and means for preventing deformation of said members while they are conducting current comprising a bracing element carried by each of said members at a point intermediate their points of engagement with said terminals each of said elements being so proportioned and positioned that the elements of adjacent members practically abut each other when the members are in the current conducting position.

3. An electric switch comprising two terminals, a plurality of independently movable spaced blades pivoted for movement about a common axis on one of said terminals and engageable with the other of said terminals for conducting electric current in parallel paths between the terminals, said blades being physically parallel while in the current conducting position, and means for preventing deformation of said blades while they are conducting current comprising a brace carried by each of said blades at a point substantially midway between the points of engagement of the blade with the terminals, each of said braces being so proportioned and positioned that the braces of adjacent blades practically abut each other when the blades are in the currentconducting position.

4. An electric switch comprising two terminals, a plurality of movable spaced elongated conducting members for conducting electric current between said terminals, said members being physically parallel While in the current conducting position, means for preventing deformation of said members while they are conducting current comprising a bracing element carried by each of said members at a point intermediate their points of engagement with said terminals and projecting from its associated member toward the adjacent member, each of said elements being so proportioned and positioned that the elements of adjacent members practically abut each other when the members are in the current conducting position, and means for varying the extent of the projection of one of said bracin elements.

5. An electric switch comprising two terminals, a plurality of movable spaced groups of spaced blade elements pivoted for movement about a common axis on one of said terminals and engageable with the other of said terminals for conducting electric current in parallel paths between the terminals, said blade elements being physically parallel While in the current conducte ing position, and means for preventing deforma tion of said blade elements while they are conducting current comprising a bracing element carried by each group of blade elements at a point substantially midway between the points of engagement of the blade elements with the terminals and extending through the associated blade elements of the group toward the adjacent blade element of another group, each of said bracing elements being so proportioned and po-- sitioned that the bracing elements of adjacent blade element groups practically abut each other when the blades are in the current conducting position and spacing means mounted on each of said bracing members between the blade elements through which the bracing member extends.

6. An electric switch comprising two terminals, a plurality of independently movable spaced groups of spaced blade elements pivoted for movement about a common axis on one of said terminals and engageable with the'other of said terminals for conducting electric current in parallel paths between the terminals, said blade elements being physically parallel while in the current conducting position, and means for preventing deformation of said blade elements while they are conducting current comprising a bracing element carried by each group of blade elements at a point substantially midway between the points of engagement of the blade elements with the terminals and extending through the associated blade elements of the group toward the adjacent blade element of another group, each of said bracing elements being so proportioned and positioned that the bracing elements of adjacent blade element groups practically abut each other when the blade elements are in the current conducting position, spacing means mounted on each of said bracing elements between the blade elements through which the bracing element extends, and means for securing said bracing elements and spacing means to their respectively associated groups of blade elements adapted to be operated to vary the extent of the projection of the bracing element from its as sociated group of blade elements.

WINTON G. HARLOW. 

